This developmental R21 is designed to develop a preventive intervention informed by the social development model to reduce substance abuse and the consequences of misuse and improve post-high school education access and retention of a population doubly vulnerable to substance abuse and poor educational attainment: youth aging out of foster care. Most of the existing programs that target youth aging out of care are fragmented, not collaboratively developed or system-ready, and fail to address the important developmental and substance abuse prevention needs of youth moving into post-high school education. Because of a lack of rigorously tested, effective prevention programs with youth aging out of foster care and the lack of system-ready comprehensive models that target age-appropriate risk and protective factors to strengthen educational supports and prevent/reduce substance misuse and the consequences of misuse among this population, we offer an innovative approach to developing a comprehensive model for positive support for youth aging out of foster care. The specific aims of this project are to (1) develop a prevention intervention approach that reduces risk factors, increases protection from substance misuse, and increases postsecondary access and success for young people exiting the foster care system; and (2) test the intervention's usability and feasibility with community stakeholders and youth aging out of foster care to prepare for a more rigorous test (e.g. R01). The intervention will include BASICS substance use prevention programming, professional educational advocacy, and college-focused mentoring. These intervention approaches address a variety of factors found to be associated with young adult substance misuse and postsecondary academic success among foster youth, including involvement in and commitment to prosocial activities and interactions, educational monitoring and support, and skills for postsecondary educational interaction, among others. Intervention development and feasibility testing, guided by Weisz and colleagues' Deployment-Focused Model of Intervention Development and Testing, includes the convening of an expert workgroup and a series of focus groups and tests of usability and feasibility with child welfare and independent living practitioners, young people with foster care experience, college personnel, and other community stakeholders in both Oregon and Washington to develop and manualize a standardized intervention approach. The goal is to develop a feasible model that is ready to be tested in an R01 rigorous randomized controlled trial.